Effect of dietary supplements of biotin,intramuscular injections of vitamin B12, or both on postpartum lactation performance in multiparous dairy cows

The current study was conducted to investigate the effects of dietary supplementation of biotin, intramuscular injections of vitamin B₁₂ (VB₁₂), or both beginning at the prepartum period on feed intake and lactation performance in postpartum dairy cows. Forty-eight dairy cows were allocated into 12 blocks, based on parity and milk yield of the previous lactation cycle, and randomly assigned to 1 of 4 treatments. Supplementation of VB₁₂ (weekly intramuscular injections of 0 or 10 mg) and biotin (dietary supplements of 0 or 30 mg/d) were used in a 2 × 2 factorial arrangement in a randomized complete block design of 12 blocks with repeated measures. The study started at 3 wk before the expected calving date and ended at 8 wk after calving. Feed intake and lactation performance (milk yield and composition) were recorded weekly after calving. Blood variables were measured on d ?10, 0, 8, 15, 29, 43, and 57 relative to calving. When VB₁₂ was given, the cows had greater feed intake, better lactation performance and lower body weight loss in the postpartum period compared with animals without injection of VB_12. The VB₁₂-injected cows had lower plasma nonesterified fatty acids and β-hydroxybutyrate concentrations but higher plasma superoxide dismutase activity compared with cows without VB₁₂. Cows fed a biotin supplement had higher milk protein yield (6 and 8 wk) and lactose yield (6–8 wk), compared with animals without biotin. However, under the present experimental conditions, we found no additive effect of a combined supplement of biotin and vitamin B₁₂ on lactation performance of dairy cows.